Oracle PL/SQL for DBAs

Transparent Data Encryption in Oracle Database 10g Release 2

When you store both the encryption key and the encrypted data in the database, another potential security hole opens up—if the disks containing the entire database are stolen, the data becomes immediately vulnerable. One way around this problem is to encrypt all the data elements and store the keys separately on a different location away from the disk drives where the data resides.

If your database is completely isolated, you may not feel that you need to encrypt its data. However, you may still want to protect the data in case of a disk theft. One solution would be to create a view to show the decrypted value. In this case, if the key is stored elsewhere, a physical disk theft will not make the data vulnerable. This approach works, but it requires an extensive and elaborate setup.

To address these types of situations, Oracle has introduced a new feature known as Transparent Data Encryption (TDE ), available starting with Oracle Database 10g Release 2. TDE uses a combination of two keys—one master key stored outside the database in a wallet and one key for each table. The same key is used for all rows in a table, and a unique key is generated for each table (as illustrated in Figure 4-7).

Figure 4-7. The Transparent Data Encryption model

With TDE, you may define a subset of columns as encrypted. For example, if a table ...